The invention relates to a method and an apparatus for spinning a synthetic multi-filament yarn.
A method and apparatus of the described type is known, for example, from U.S. Pat. No. 3,103,407, wherein a freshly spun synthetic filament yarn (polyester) is advanced by means of a withdrawal roll or godet from a spin zone to a draw zone and drawn between the withdrawal roll and a draw roll or godet. In this process, the yarn is heated in two stages by contacting the heated withdrawal roll and a heated metal plate directly adjacent thereto. The withdrawal roll is heated to a temperature from 60 to 90.degree. C. and the metal plate to a temperature from 160 to 200.degree. C. The withdrawal speed is in a range of less than 1,000 m/min.
The above-described method has the disadvantage that the heating of the yarn is dependent exclusively on the contact between the heated surfaces and the yarn. Furthermore, the long contact length and high contact force lead to increased yarn frictions, which have disadvantageous effects on the yarn quality. These adverse effects amplify rapidly at higher withdrawal speeds, so that an even heat transfer is no longer possible.
It is an object of the present invention to achieve in the thermal treatment of an advancing synthetic multi-filament yarn, which may be polyester, polyamide, polytrimethylene terephthalate, and polypropylene, a uniform heating of the yarn with a correspondingly uniform drawing, and uniform, well adjustable yarn properties.